Indentation plastic flow in compliant wafers was investigated. Compliant substrates were fabricated by bonding two (001) wafers having a suitable twist angle. A dense network of pure screw dislocations was found in the interface. Berkovitch indentation was carried out on the substrates, to maximum loads which ranged from 600 to 4500μN. Perfect dislocation hoops were observed at the edge of the plastic zone, and most of these had Burgers vectors which were inclined with respect to the surface. At loads above 1500μN, perfect dislocations with their Burgers vector parallel to the sample surface were also observed. At loads below 4500μN, such dislocations resembled closed hairpins with 2 screw segments; one of which was pinned. Stacking faults appeared, at loads above 1500μN, only when perfect b = (a/2)[¯110] dislocations extended.

Nano-Indentation of GaAs Compliant Substrates. G.Patriarche, E.Le Bourhis: Philosophical Magazine A, 2000, 80[12], 2899-911